Questions tagged [hvac]

(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.

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Overheating/airflow issue with gas furnace: 3 different HVAC techs, 3 different diagnoses

I'm a new homeowner (1.5 years), and there was a new gas furnace installed just before we moved in. A month or so ago, the furnace started making a whistling noise for a second or two just at the ...
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0answers
49 views

How to add Honeywell wireless thermostat to furnace with "add a wire" installed

I am trying to wire up from an older 4 wire RADIO CT30E thermostat to a smart wireless HONEYWELL RTH9580WF1013 thermostat. A post on the HONEYWELL site - or connected to it - suggested moving the ...
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1answer
97 views

What is this air handling unit in my new UK flat?

Friends just moved into a new, modern flat (UK) and this unit was on the wall in one room, permanently wired on. Any help identifying? There's an internal mesh and an external vent, and a label on ...
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How to wire a 2 stage heat pump with gas furnace

I bought a new house last year and this is the first winter I've been in it. It have a gas furnace that we've been using as the only heat source. The other day, I went to clean the condensor coils and ...
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2answers
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Seweage smell ONLY from AC vent in bathroom

I recently started installing new floor in our bathroom. I of course took out the sink and toilet, which were left unconnected for about a day and a half (will not do that again). The sink and toilet ...
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0answers
27 views

My furnace has been going on and off erractically

Furnace goes on within 2-3 minutes of stopping. It runs for about 4 minutes and goes off. 2 minutes it goes on. Even after the temp. has reached 70. The outside temp is not that cold compared to ...
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0answers
44 views

Viconics E117 / P117 replacement by Honeywell Lyric T5

I just moved into my old neighbourhood after being away for 15 years. We bought this old house (1957) and it seems that the heating/cooling system got changed through times (Oil to electric in 2001 ...
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0answers
65 views

Question about bleeding baseboard heating

I have a house built in 1949 with baseboard heating (5 loops), and I don't seem to be able to find any bleeder valves at the baseboards themselves. One of the loops in particular is making an awful ...
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19 views

How to install Aprilaire humidifier with into furnace with multiple zones

My home has very low humidity during winter in CT, and I started looking into whole home humidifiers. I'm looking at the Aprilaire 600. I have an oil furnace with 3 zones and I'm trying to understand ...
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4answers
74 views

Is DIYing a replacement of Electric Furnace and Air conditioner worth it?

My Air conditioner does not produce cold air, however heater part in Furnace works just fine. Air conditoner Unit is at least 20 years old and have no coolent left in the system. I am looking to ...
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Honeywell 5-wire zone valve wiring

Update: I was able to successfully re-wire a spare wire to my Google Nest Thermostat 2020 AND reconnect power to the C-Wire of my 3rd generation Nest Learning Thermostat. Turns out the 3-amp fuse in ...
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Noise from roof top Make up air exchanger

A replacement rooftop make up air unit was installed in our condo in Spring of 2021. This is the Chicago area. Soon after a noise that sounded like a recurring timpani drum strike began. It only ...
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1answer
52 views

Removing a hvac branch duct

I'm looking to finish my basement, and wanted to remove all forced air ducts at the ceiling and do floor heating for the basement. Since I'm a noob in hvac, couple questions: Can I just cut off these ...
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7answers
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Why is my house energy efficient only in winter?

My electric utility company sent me a graph of my home's electricity usage over time as shown in the picture below. My home beats what the company considers as efficient homes in the neighborhood when ...
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1answer
46 views

How many elbows are too many

In our high efficiency furnace installation there are 13 90 degree elbows. The furnace installation manual suggests a maximum of 8. What problems can this cause?
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Wiring a damper to an erv

HVAC installer didn't put a mechanical damper in the fresh air supply line, so I get cold air Back feeding. The erv 24v line is hooked to my thermostat. Do I hook the 24v damper to the same line or? ...
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1answer
60 views

Second opinions on thermal photo of HVAC duct

One of the supply ducts in the (second floor) nursery always seems to have a smell of fiberglass coming through it. It is a 2.5x10 duct run through the wall. I have long suspected this duct might be ...
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1answer
40 views

Replacing 1-Stage Furnace & A/C for Comfort & Efficiency

Need opinions on imminent HVAC work in a Massachusetts home. House and HVAC system descriptions below: House: ~45yrs, 1850 sqft, 2 floors + unfinished basement (furnace located in basement). Each ...
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2answers
53 views

Heat pump size, given existing gas furnace size

If I have a furnace with some BTU rating, and given the outside temperature, is there a way, or a web site, or whatever, that would tell me what rating an air-source heat pump would be need, to supply ...
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0answers
25 views

How to route/replace HVAC plenum/trunk lines through a poorly designed foundation wall hole with a gas pipe in the way on the other side

New homeowner of a 1959 constructed house. Surprisingly, only 4 owners (including myself), with the last 2 each having it for about 20 yrs and each seemed to be DIYers - not necessarily choices I ...
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2answers
56 views

Wiring an AC disconnect during rough in phase of new construction?

What is the proper way to run wire to an AC disconnect box with new construction, knowing that there will eventually be siding on top of a rainscreen? Mockup Here is a mockup of my wall assembly. ...
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1answer
49 views

Is it possible to add a C-wire to a Honeywell R7284 Oil Primary Control (current two-wire system)?

I currently have a two-wire system (R/W) going to my thermostat. The furnace is an oil heat system with a blower to force air. There is currently a Honeywell R7284 Oil Primary Control where the ...
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1answer
54 views

Air return competes with bathroom fan?

Can my air return be preventing my bathroom exhaust fan from drawing air? We have a terrible time with moisture building up during showers. The air return is on the hall wall directly opposite the ...
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1answer
29 views

Installing mini split system without wall core and running line set in attic

So the mini split I purchased calls for 3.5 inch hole to be cored from the handler unit to the outdoor compressor. It’s always painful for me to see beautiful poured block walls destroyed, so my ...
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1answer
44 views

Where to connect common wire from thermostat to First Co. air handler?

I'm trying to install a new Honeywell WiFi 9000 thermostat which requires a common wire. When I removed my old thermostat, I can see there are two extra wires in my wall (black and orange wire) that ...
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2answers
45 views

Electric furnace fan runs in fan-on (no heat) but sometimes not auto. If I run fan-on a few minutes then switch to auto it sometimes fixes problem

Over the last couple of winters once in awhile I would notice that my electric furnace wouldn’t kick on when the thermostat would click on to the temperature setting. I don’t remember how I figured ...
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0answers
44 views

How to configure Honeywell combine W2/AUX/E terminal for Emergency heat?

I have a Honeywell RTH9585WF1012 to control my forced air furnace system which has: Cool: 1-stage heat pump Heat: 1-stage heat pump (same) + Expensive emergency gaz heat from furnace. Older ...
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1answer
92 views

Split AC Unit won't turn on after an explosion sound

I have a Split AC Unit and it had been working fine for a while, but one day I turned on the switch for my AC and I heard a loud explosion sound emanate from the indoor unit. After that, I couldn't ...
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0answers
49 views

Where to start diagnosing a Bryant 926TA error code 3-3 "LIMIT CIRCUIT FAULT"

My furnace was installed in 2019. Since that time, I have occasionally noticed an odd behavior: when there is a large-ish gap between the current temperature and desired temperature (say, overnight I ...
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5answers
3k views

How can I protect a frozen heat pump in cold weather while waiting for service?

Yesterday I noticed that my Carrier heat pump was struggling to keep up with my thermostat settings inside the house. It was around 35°F (2°C) outside, I had the thermostat set at 72°F (22°C), but the ...
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1answer
28 views

Can I move HVAC register to bay on the left?

I'd like to move register to the bay of the left. What kind of elbows can I use so that duct can go through the stud? If there is no such elbow, what are my options?
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13 views

Central AC Unit not blowing cold air

OK, so my Central AC Unit has acted a little funny shortly after I purchased the house I'm in now. It worked fine besides occasionally when I would try and drop the thermostat multiple degrees at a ...
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2answers
91 views

Should chunks of fiberglass looking material be present in my bypass humidifier?

See the attached photo. It's only really visible on the top here, but this fiberglass looking material (duct liner?) is present on all four sides. Should I remove this material, or otherwise work to ...
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2answers
2k views

(When) Does room messiness affect water heater efficiency?

I have what I think of as a "standard US electric standby water heater." I will update this when I know the model; I am out of town right now. It is located in a cold, cluttered closet in a ...
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0answers
17 views

How do I wire Honeywell RTH6500 Thermostat?

I have an old battery powered HW thermostat using 4 wires (W Y G R). I intend to replace it with a Honeywell RTH6500WF using a 24v power adapter, hook the adapter’s 2 wires directly to the baseplate ...
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0answers
14 views

I have a Nest 3rd generation thermostat and it wont turn on the furnace

I have a Nest 3rd generation thermostat and it wont automatically turn on my furnace i have to the nest to off then turn back to On to get the furnace to start. It was running fine for about 2 months ...
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1answer
18 views

Honeywell hz322 heat pump with aux heat

I get heat and aux separately but not together. I checked the 322 and it's calling for both, but only heat light is on. I only have w1 wired... Is this the problem? I see is says to tie w1 and w2 ...
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1answer
38 views

Temporary Insulation - Window Fan

I live in an apartment without adequate kitchen ventilation. I like doing a lot of wok cooking, which tends to result in enormous amounts of smoke - tripping smoke alarms and getting into all of my ...
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9answers
6k views

Should my neighbor run their AC refrigerant lines through my garage? [closed]

I live in a 2-unit town home. I have installed an AC on the side of my unit. My neighbor would like to install an AC for their unit. However the city codes will not allow them to install it on the ...
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2answers
57 views

Trying to understand NYC code for using common corridors as return air

I wanted to understand the NYC building code in this situation: I'm in a 2 family brownstone home with a shared basement (laundry room for the 1st-floor unit and a storage room for the 2nd-floor unit, ...
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3answers
67 views

If you plug a 100v mini split AC into a wall outlet rated at 15a or 20a, what possible complications could occur, if any?

A 110v mini split AC is typically wired to an AC disconnect and then into the breaker box. However, many have simply wired it directly into a standard outlet receptacle, or even to a standard plug, to ...
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0answers
19 views

Anderson air unit outside works then doesn't

Anderson Air RPHP13A30P-1A I have paid 2 different people to work on unit. One just reset the system the other put 2 lbs in. After doing my own testing, capacitor tested bad and fan had no continuity ...
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3answers
59 views

How to size inducer motor capacitor?

I have an ICP gas furnace which won't start and I've diagnosed the problem to a bad capacitor on the inducer motor. The motor spins freely and measures good resistance, so I'm going to try replacing ...
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0answers
25 views

Where to replace heat return vent

I live in a 12,00 sqare foot ranch. The furnace is in the basement but both return registers are on the main floor right opposite each other in the main hallway. I'm remodeling my main bathroom. The ...
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0answers
12 views

Aprilaire 600 to Fedders furnace

Wiring issue. I have installed the unit, an Aprilaire 600. When the humidifier is OFF, the heat and fan operate normally. However, when the humidifier is ON, the heat and fan come on normally but ...
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1answer
53 views

HVAC - noisy preheat

When the heat comes on I hear a noticeably loud whirring sound in the beginning. It only lasts for a couple minutes and then quiets down while the fan continues to blow heat throughout the home. I ...
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2answers
64 views

Why are some HVAC UVC air cleaners listed as "return air models"?

I would like to install a UV Air cleaner, but most of them seem to be listed as return air models. Due to the .. odd nature of my furnace setup, I would really like to install this in the plenum that ...
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2answers
156 views

What are the pros and cons of having a return "duct" in each room vs. 2-3 large shared returns?

The return "ducts" in my house are run through building cavities, and I've just about had it dealing with them. I do have a laundry chute to sacrifice. I am toying with the idea of using ...
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0answers
11 views

New Condenser FAN motor not turning on with the DF2 on new Goodman Defrost Control Board

I bought the following Defrost Control Board PCBDM101S for my Goodman CPLI41-1 Condenser because I found a black scorched mark on the old board. I thought this was the main reason for my fan motor not ...
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0answers
27 views

Is my HVAC condenser fan motor wired incorrectly?

My condenser fan motor stopped working and I noticed black scorched marks on the Defrost Control Board where the fan connection is (near DF2 and the relay that is used to run the fan). The HVAC ...

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